Daniel I. Branovan
, New York Ear, Nose and Throat Institute, USATitle : A search for causes of rising incidence of differentiated thyroid cancer in children and adolescents after Chernobyl and Fukushima: Comparison of the clinical features and their relevance for treatment and prognosis
Abstract
The incidence of Differentiated Thyroid
Cancer (DTC) is steadily increasing globally. Epi-demi ologists usually explain
this global upsurge as the result of new diagnostic modalities, screening and
overdiagnosis as well as results of lifestyle changes including obesity and
comorbidity. However, there is evidence that there is a real increase of DTC
incidence worldwide in all age groups. Here, we review studies on pediatric DTC
after nuclear accidents in Belarus after Chernobyl and Japan after Fukushima as
compared to cohorts without radiation exposure of those two countries.
According to the Chernobyl data, radiation-induced DTC may be characterized by
a lag time of 4–5 years until detection, a higher incidence in boys, in
children of youngest age, extrathyroidal extension and distant metastases. Radiation
doses to the thyroid were considerably lower by appr. Two orders of magnitude
in children and adolescents exposed to Fukushima as compared to Chernobyl. In
DTC patients detected after Fukushima by population-based screening, most of
those characteristics were not reported, which can be taken as proof against
the hypothesis, that radiation is the (main) cause of those tumors. However,
roughly 80% of the Fukushima cases presented with tumor stages higher than
microcarcinomas pT1a and 80% with lymph node metastases pN1. Mortality rates in
pediatric DTC patients are generally very low, even at higher tumor stages.
However, those cases considered to be clinically relevant should be followed-up
carefully after treatment because of the risk of recurrencies which is expected
to be not negligible. Considering that thyroid doses from the Fukushima
accident were quite small, it makes sense to assess the role of other
environmental and lifestyle-related factors in thyroid carcinogenesis.
Well-designed studies with assessment of radiation doses from medical
procedures and exposure to confounders/modifiers from the environment as e.g.,
nitrate is required to quantify their combined effect on thyroid cancer risk.
Biography
Daniel Igor Branovan is the founder and president
of project Chernobyl, un-accredited not-for-profit international organization
based in New York. He is a US-trained head and neck surgeon and serves as director
and chair of the New York Ear, Nose and Throat Institute. He has received his
medical training at Stanford University School of Medicine and Harvard
University School of Public Health.